The invention relates to ventilation to control temperature, humidity and air quality in confined spaces. Ventilation of confined spaces involves movement of fresh air thereto and removal of vitiated air therefrom. A confined space to which the invention applies may be a room or an attic in a domestic building, an area in a farm building for storing produce or accommodating animals, a workspace in an industrial establishment, in an underground formation such as a mine or tunnel or in a road, rail or water vehicle. The air in such confined spaces may be spoiled because of depletion of the oxygen content of the air and/or due to the presence of odours, noxious gases, smoke, dust and the like.
Ventilation apparatus for this purpose is well known and many systems such as powered, wind-assisted and convective arrangement have been proposed. To achieve effective circulation of air, the inlet for fresh air has generally been located at a lower level than the outlet for spoiled air which has usually been at ceiling or roof level. Commonly, the outlet has been a roof ventilator comprising a substantially vertical shaft or duct passing through the roof of the structure enclosing the confined space or mounted adjacent to the roof As the open top end of the duct is exposed to atmosphere, it has usually been provided with a cap or canopy which does not impede the outflow of air from the duct but provides some protection from atmospheric deposits such as rain and snow entering the duct and passing to the confined space. However, wind-borne dust, rain, spray and snow can still pass under the cap and into the duct and pass to the confined space, even when some wind-assisted devices such as turbine ventilators are installed.
There have been some prior proposals intended to avoid wind driven rain and other material entering the ventilating opening in the roof of a structure. There are also some prior wind directed devices for ventilators and chimneys.
In U.S. Pat. No. 4,989,503 (Shank), there is disclosed a wind-directed roof ventilator comprising a hood covering an elongated opening in the roof of a farm building. The hood is pivotally mounted and is capable of side-to-side movement to two oppositely located limit positions by means of a drive motor controlled by a wind-directed-responsive vane mechanism. In the event of particular wind directions, the position of the hood is varied to minimize the risk of wind-driven rain from entering the ventilating opening.
U.S. Pat. No. 1,420,141 (Pennington) discloses a flue hood for preventing back draft and the entry of rain to the flue. A V-shaped hood is pivotally mounted above the flue opening and is adapted to oscillate about a horizontal axis to cover and uncover opposite sides of the flue. Wind pressure actuated means causes the hood to tilt to cover the side of the flue to windward.
U.S. Pat. No. 4,593,610 (Chabot) discloses a wind directed automatic damper for a chimney flue designed to keep constant the chimney draft despite varying wind velocity and direction.
U.S. Pat. No. 2,601,423 (Allman et al) discloses a roof ventilator for exhausting air from a building. The ventilator has a cap and baffles intended to prevent wind or wind driven rain or snow from entering the building through the ventilator and a movable damper blade to control exhaustion of air from the building.
U.S. Pat. No. 5,498,205 (Knowles et al) discloses a roof ventilator having exhaust ports in opposite vertical sides and deflecting baffles to allow air and fumes from the interior of the building to be exhausted generally horizontally while preventing wind driven rain, snow and like from entering the building through the ventilator. An air control baffle is provided to control the exhaust.
U.S. Pat. No 2,923,225 (Massey) discloses a roof ventilator for a building. The ventilator is of generally rectangular cross-section and has downwardly facing exhaust ports in opposite sides and a damper blade for controlling the flow of air from the building.
U.S. Pat. No. 2,214,183 (Seymour) discloses a roof ventilator, extending along a roof ridge, with curved baffles forming downwardly facing exhaust ports on opposite sides of the ridge.
It is an object of the invention to provide a roof ventilator having a tilting hood which is designed to operate as a combined wind assisted and convective ventilator that avoids the ingress of wind and wind-borne material.
The roof ventilator of the invention is simple in operation in that it requires the hood of the ventilator to be mounted on a single pivot bearing allowing the hood to tilt away from the wind thus increasing the ventilation rate due to the suction caused by wind flowing around the hood and thus positioning the hood to deflect wind and wind-borne material from the ventilator opening irrespective of wind direction. The invention provides a tilting hood ventilator which is simple in construction with few moving parts.
In accordance with the invention, a ventilator for a structure enclosing a confined space comprises a duct adapted to be mounted in a substantially upright position having an open upper end exposed to the atmosphere and a lower end communicating with the confined space, a substantially symmetrical hood having a base located substantially at the apex of the hood and a skirt fixed to the base and depending therefrom, a socket in the base opening on the underside thereof, a rigid support having a lower end connected to said duct and an upper end, a bearing fixed to the upper end of the support and seated in the socket so that the base of the hood is supported in a position spaced above the upper end of the duct with the depending skirt surrounding the upper end of the duct, the arrangement being such that, in the absence of wind, the hood is spaced from the duct and, in the presence of wind from any direction, the hood is tilted by the wind so that the skirt is lowered on the windward side thus increasing the ventilation rate and thus positioning the hood to deflect wind and wind-borne material from the ventilator opening.
The rigid support may be fixed to the ventilator duct. Alternatively, the support may be mounted so that it can raise or lower the hood to open or close the ventilator duct.